Fourteen PETS systems will be implanted and evaluated in seven miniature pigs. Eight will have cables and two will be powered. All of the implanted PETS will have fibronectinized PTFE as the interface if preliminary tissue adhesion studies suggest this is worthwhile. Five systems will be evaluated at six months and the remaining systems allowed to remain implanted indefinitely. Each system will be evaluated clinically, bacteriologically, biochemically, and histopathologically. Thermo Electron will provide the appropriate hardware and will perform in vitro evaluation of these systems.